Over the past several years, we have studied self reported levels of physical activity in the Baltimore Longitudinal Study of Aging subjects. Increasing age is associated with a decline in physical activity, cardiovascular fitness, muscle strength, and muscle mass. These changes contribute to sarcopenia and frailty in the elderly. We have been interested in how changing physical activity impacts on these other activity related processes. In the last year, we have reported on the activity questionnaire administered to subjects in the Baltimore Longitudinal Study of Aging over 4 decades. The 97 activities were divided into three categories based on published levels of intensity in MET units: low level activity (<4 METS), moderate level activity (4-6 METS), and high level activity (>6 METS). We examined secular trends in leisure time physical activities (LTPA) in 1359 men from who were evaluated one or more times over the period from 1958 to 1998 and 840 women from 1978 to 1998. Evaluations of LTPA were averaged for each decade. The prevalence of a sedentary lifestyle in each decade was assessed based on compliance with widely publicized recommendations for participation in physical activity. All analyses were adjusted for age, education and race differences across decades. Median high intensity LTPA, defined as activities >6 METS, increased from 30 to 80 MET-minutes/day from the 1960's to the 1990's for men (p<0.01) but did not change between the 1970's and the 199'?s in women. Moderate intensity LTPA, defined as 4-5.9 METS, did not change significantly over these periods in either sex. The percentage of sedentary men, defined as those performing < 40 MET-minutes/day of high intensity LTPA, declined across the four decades whereas for women it did not change significantly. For those over 60 years old, time trends in high intensity LTPA resembled those for the overall sample. In contrast, smoking rates declined from 35% to <10% in men and from 24% to 5% in women over these periods. In this health conscious sample across a broad age range, national recommendations appear to have made modest progress in decreasing the proportion of sedentary adults. How to increase participation in physical activity has become a major health issue. The answer will lie in offering a variety of programs that allow for individualization. We reported an intervention that explored an alternative approach to increase activity in patients with osteoarthritis of the knee. In a pilot study, two groups of subjects were evaluated. The first participated in an educational program while the second had the educational program and in addition were supplied with a pedometer to assess their daily activities. The use of the pedometer was associated with an increase in the amount and speed of walking done by these patients. At present, a project is underway where we are using the same strategy and applying it to military reservist who do not meet fitness requirements for a 2 mile run. The goal is to increase their overall activity levels by making them more aware of what they are actually performing, and to set reasonable goals to increase activity during the course of their busy schedules.